Simultaneous Chest Compression and Ventilation at High Airway Pressure during CPR.

Chandra N, Rudikoff M, Weisfeldt ML Lancet 1980 Vol 1 Pages 175-178

The authors note that in most patients, blood flow during CPR results from a rise in intrathoracic pressure rather than direct heart compression. Intrathoracic pressure was increased by the use of positive-pressure ventilation synchronous with sternal compression in eleven arrested patients who were intubated. A computer system allowed 15-30 second periods of alternation between conventional CPR and new CPR (rate of 40/minute, 60% compression duration, and simultaneous ventilation at airway pressures from 60-110 cmH20). Compression force was identical with the two methods. New CPR increased mean systolic radial artery pressure significantly from 40.6+/-4.4 to 53.1+/-3.9 mmHg for 14 runs in nine patients. In 15 runs in ten patients, an index of carotid flow increased with new CPR to 252% (range 113-643%) of control values. Lowering airway pressure during new CPR lowered flow index and arterial pressure, confirming that these increases with new CPR were due to higher intrathoracic pressure. Despite the dramatic increases in flow index and blood pressure seen with new CPR, the authors advise against rapid clinical implementation of this approach. While dog studies showed no impairment of oxygenation, there is no data in man on long-term effects on oxygenation or CO2 removal. Nor is there evidence of long-term benefit in terms of augmentation of flow, and the possibility of carotid collapse during long-term new CPR has yet to be ruled out. Real benefit, in terms of survival or lessened cerebral dysfunction, has yet to be demonstrated, however the technique looks promising and clinical trials seem warranted.